Create a "sort support" interface API for faster sorting.

This patch creates an API whereby a btree index opclass can optionally
provide non-SQL-callable support functions for sorting.  In the initial
patch, we only use this to provide a directly-callable comparator function,
which can be invoked with a bit less overhead than the traditional
SQL-callable comparator.  While that should be of value in itself, the real
reason for doing this is to provide a datatype-extensible framework for
more aggressive optimizations, as in Peter Geoghegan's recent work.

Robert Haas and Tom Lane

1 files changed, 106 insertions, 0 deletions

diff --git a/src/backend/access/nbtree/nbtcompare.c b/src/backend/access/nbtree/nbtcompare.c
index 23f2b61fe9..f86b7551d2 100644
--- a/src/backend/access/nbtree/nbtcompare.c
+++ b/src/backend/access/nbtree/nbtcompare.c
@@ -49,6 +49,7 @@
 #include "postgres.h"
 
 #include "utils/builtins.h"
+#include "utils/sortsupport.h"
 
 
 Datum
@@ -69,6 +70,24 @@ btint2cmp(PG_FUNCTION_ARGS)
 	PG_RETURN_INT32((int32) a - (int32) b);
 }
 
+static int
+btint2fastcmp(Datum x, Datum y, SortSupport ssup)
+{
+	int16		a = DatumGetInt16(x);
+	int16		b = DatumGetInt16(y);
+
+	return (int) a - (int) b;
+}
+
+Datum
+btint2sortsupport(PG_FUNCTION_ARGS)
+{
+	SortSupport	ssup = (SortSupport) PG_GETARG_POINTER(0);
+
+	ssup->comparator = btint2fastcmp;
+	PG_RETURN_VOID();
+}
+
 Datum
 btint4cmp(PG_FUNCTION_ARGS)
 {
@@ -83,6 +102,29 @@ btint4cmp(PG_FUNCTION_ARGS)
 		PG_RETURN_INT32(-1);
 }
 
+static int
+btint4fastcmp(Datum x, Datum y, SortSupport ssup)
+{
+	int32		a = DatumGetInt32(x);
+	int32		b = DatumGetInt32(y);
+
+	if (a > b)
+		return 1;
+	else if (a == b)
+		return 0;
+	else
+		return -1;
+}
+
+Datum
+btint4sortsupport(PG_FUNCTION_ARGS)
+{
+	SortSupport	ssup = (SortSupport) PG_GETARG_POINTER(0);
+
+	ssup->comparator = btint4fastcmp;
+	PG_RETURN_VOID();
+}
+
 Datum
 btint8cmp(PG_FUNCTION_ARGS)
 {
@@ -97,6 +139,29 @@ btint8cmp(PG_FUNCTION_ARGS)
 		PG_RETURN_INT32(-1);
 }
 
+static int
+btint8fastcmp(Datum x, Datum y, SortSupport ssup)
+{
+	int64		a = DatumGetInt64(x);
+	int64		b = DatumGetInt64(y);
+
+	if (a > b)
+		return 1;
+	else if (a == b)
+		return 0;
+	else
+		return -1;
+}
+
+Datum
+btint8sortsupport(PG_FUNCTION_ARGS)
+{
+	SortSupport	ssup = (SortSupport) PG_GETARG_POINTER(0);
+
+	ssup->comparator = btint8fastcmp;
+	PG_RETURN_VOID();
+}
+
 Datum
 btint48cmp(PG_FUNCTION_ARGS)
 {
@@ -195,6 +260,29 @@ btoidcmp(PG_FUNCTION_ARGS)
 		PG_RETURN_INT32(-1);
 }
 
+static int
+btoidfastcmp(Datum x, Datum y, SortSupport ssup)
+{
+	Oid			a = DatumGetObjectId(x);
+	Oid			b = DatumGetObjectId(y);
+
+	if (a > b)
+		return 1;
+	else if (a == b)
+		return 0;
+	else
+		return -1;
+}
+
+Datum
+btoidsortsupport(PG_FUNCTION_ARGS)
+{
+	SortSupport	ssup = (SortSupport) PG_GETARG_POINTER(0);
+
+	ssup->comparator = btoidfastcmp;
+	PG_RETURN_VOID();
+}
+
 Datum
 btoidvectorcmp(PG_FUNCTION_ARGS)
 {
@@ -237,3 +325,21 @@ btnamecmp(PG_FUNCTION_ARGS)
 
 	PG_RETURN_INT32(strncmp(NameStr(*a), NameStr(*b), NAMEDATALEN));
 }
+
+static int
+btnamefastcmp(Datum x, Datum y, SortSupport ssup)
+{
+	Name		a = DatumGetName(x);
+	Name		b = DatumGetName(y);
+
+	return strncmp(NameStr(*a), NameStr(*b), NAMEDATALEN);
+}
+
+Datum
+btnamesortsupport(PG_FUNCTION_ARGS)
+{
+	SortSupport	ssup = (SortSupport) PG_GETARG_POINTER(0);
+
+	ssup->comparator = btnamefastcmp;
+	PG_RETURN_VOID();
+}